The invention relates to a switch matrix composed of a plurality of optically non-linear, e.g., bistable, elements disposed as optically active layers on a common substrate surface to two methods of producing the switch matrix.
Optically non-linear elements may operate as light switches. Simplified, this process can be described as follows.
If the power of a laser beam which irradiates such an element is increased to beyond a certain threshold, a sudden rise in the transmitted light results and a sudden drop in the reflected light. This effect makes it possible to employ such optically non-linear components as switch elements for digital optical data processing. For this use, a two-dimensional arrangement of such switches is of particular interest -- a switch matrix in which the individual switching elements have lateral dimensions in an order of magnitude of 10 .mu.m.times.10 .mu.m and are positioned as closely together as possible.
Such a switch matrix is disclosed in "Optical Bistability III", published by Springer-Verlag, ISBN 3-540-16512-6, pages 39-41. This two-dimensional arrangement of switching elements was realized by means of MBE (molecular beam epitaxy). On a plate-shaped, 0.2 .mu.m thick substrate of Al.sub.0.4 Ga.sub.0.6 As,0 4Ga0 6As, optically active GaAs layers of a size of 9.times.9 .mu.m.sup.2 and a thickness of 1.5 .mu.m are applied at a mutual spacing of 20 .mu.m. Due to the mutual influence, the spaces between the elements cannot be reduced further. Moreover, the manufacturing process is complicated and expensive.
However, optically non-linear switching elements are known which can be produced by precipitating thin layers on a substrate without requiring epitaxial growth on the substrate. A typical example is the material ZnSe which is precipitated on a glass or sapphire substrate. In the past, it has not been attempted to spatially separate individual spots of such materials from one another on the substrate, rather various spots in the same layer are addressed in parallel by spatially limited laser light bundles. The definition of individual switching elements according to this process was thus effected by the spatial expanse of the laser light. Thermal contact and diffusion of charge carriers necessitate a spacing of the illuminated spots operating as switching elements in an order of magnitude of millimeters, instead, as desired, in an order of magnitude of microns, so as to limit crosstalk to permissible values. This solution is unsatisfactory because, due to the required relatively large distance between the individual switching elements, such a switch matrix can accommodate fewer switching elements by orders of magnitude than is desirable.